1. Field of the Invention
This invention relates generally to cameras and, more particularly, to cameras with pointing aids.
2. Description of the Related Art
Cameras serve as image capture devices, taking pictures of an ambient scene through an objective lens. For example, a photographic still camera stores an image, either photoelectronically into memory or photochemically onto a filmstrip, when an image capture button, such as a shutter button, is fully depressed. In a still camera, pressing the shutter button causes a shutter to be tripped, which permits light from the scene to pass through the objective lens and fall onto a photodiode array or film strip located at a focal plane of the lens. A video camera or movie camera captures a sequence of images that, when played back, presents the illusion of motion.
A camera user typically looks through a camera viewfinder to aim the camera at a particular point or object in the scene that is of interest. At times, such as under low light conditions or in a crowded scene, it can be difficult to judge the point in the scene on which the camera is directed. At other times, such as when tracking fast moving objects in the scene or when picture taking discretion is desired, it might be desirable to aim the camera without looking through the viewfinder at all.
For these and other reasons, some cameras are provided with a variety of pointing aids that help a camera user determine where in the scene the camera is directed. Generally, the pointing aid comprises a source of visible light whose output beam is substantially aligned with the optical axis of the camera objective lens. If an object in a scene is illuminated with the beam, the camera user is assured that light from the object will be directed through the objective lens and onto the focal plane for image capture. Placing the pointing aid beam on an object of interest can be done with or without looking through the viewfinder.
For example, U.S. Pat. No. 5,189,463 to Capper et al. describes a video camera with a laser pointing device that is said to obviate the need for looking through a viewfinder to aim the camera. British Patent No. 2 252 836 describes a flashlight and photographic camera combination that optionally can include a laser, which is said to emit a beam that is aligned with the camera lens so as to indicate the object of which a photograph will be taken. The laser is said to make it easier to orient the camera lens.
Although such systems permit easier aiming of a camera, the conditions under which the camera is used can vary widely. For example, under bright ambient light conditions, it can be difficult to see the beam and discern the object on which the pointing aid beam is falling. At the same time, the beam should not be so bright that the power source supplying power to the emitter is unnecessarily drained. Thus, it would be desirable to control the output power of the emitted beam so that it is readily discernable to the camera user under a variety of conditions while power consumption is reduced to only that which is necessary.
While it is important that the emitted beam should be sufficiently bright to be readily seen by the camera user, it also is important that the beam not be so extraordinarily bright that it distracts persons or animals in the scene. In addition, it is important that the output power of the beam not be so great that objects, persons, or animals in the scene might be damaged by the beam. For example, if the pointing aid beam were produced by a device such as a laser and the beam were to enter through the pupil of a person or animal in the scene, and if the laser output power was sufficiently great, then the laser beam could possibly cause damage to the retina. Thus, it again would be desirable to permit control over the pointing aid beam output power.
From the discussion above, it should be apparent that there is a need for a camera with a pointing aid beam that is visible under a variety of ambient conditions, does not use excessive power, and reduces the risk of damage or injury to objects, persons, and animals in the ambient scene. The present invention fulfills this need.